JP2606914B2 - Method for producing polyimide having good thermal stability - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a polyimide resin for melt molding. More specifically, the present invention relates to a method for producing a polyimide having good heat stability and excellent moldability.

[Prior art] Conventionally, a polyimide obtained by a reaction between a tetracarboxylic dianhydride and a diamine has excellent mechanical strength and dimensional stability, in addition to its high heat resistance, and has both flame retardancy and electrical insulation properties. In addition, they are used in fields such as electric and electronic equipment, aerospace equipment, and transport equipment, and are expected to be widely used in fields where co-heat resistance is required in the future.

Conventionally, various polyimides exhibiting excellent characteristics have been developed.

However, even if it has excellent heat resistance, it does not have a clear glass transition temperature, so if it is used as a molding material, it must be processed using a method such as sintering, and it has excellent workability. It has a low glass transition temperature, is soluble in halogenated hydrocarbons, is not satisfactory in terms of heat resistance and solvent resistance, and has advantages and disadvantages in performance.

On the other hand, the present inventor has previously described the following formula (IV) as a polyimide having excellent mechanical properties, thermal properties, electrical properties, solvent resistance, etc. and having heat resistance. (Wherein, R represents an aliphatic group having 2 or more carbon atoms, a cycloaliphatic group,
Represents a tetravalent group selected from the group consisting of a monocyclic aromatic group, a condensed polycyclic aromatic group, and a non-condensed polycyclic aromatic group in which the aromatic groups are connected to each other directly or by a bridge member. . A polyimide having a repeating unit represented by the following formula was found (JP-A-62-50372). The above-mentioned polyimide is a novel heat-resistant resin having many good physical properties.

However, although the above-mentioned polyimide shows excellent fluidity and is a polyimide having good processability, if it is kept at a high temperature for a long time (for example, during injection molding, if it stays in a cylinder for a long time at a high temperature), The fluidity of the molten resin gradually decreases, and as a result, the moldability decreases.

[Problems to be Solved by the Invention] An object of the present invention is to provide an excellent polyimide which, in addition to the excellent properties inherent to polyimide, has good thermal stability and does not deteriorate in moldability even when kept at a high temperature for a long time. It is to provide a manufacturing method.

[Means for Solving the Problems] The present inventors have conducted intensive research to solve the above problems, and have completed the present invention. That is, the present invention provides: And (b) an aromatic diamine represented by the following formula (II): (Wherein, R represents a tetravalent group described below) and (c) the following formula (III) Z-NH ₂ (III) (wherein Z is described later) (D) the amount of the aromatic diamine is 0.9 to 1.0 mole ratio per mole of tetracarboxylic dianhydride, and the amount of the aromatic monoamine is 0.00 per mole of carboxylic dianhydride
Reacting at a molar ratio of 1 to 1.0, characterized by the formula (IV) (Wherein R is as defined in formula (II).) Production of a polyimide having good thermal stability, comprising a repeating unit represented by the formula: wherein the terminal of the polymer is a group of formula (IV-a) Is the way.

(In the formula, R and Z are as defined above.) As the aromatic diamine represented by the formula (I) used in the method of the present invention, bis {4- [4- (4-aminophenoxy) ) Phenoxy] phenyl} sulfone.

In addition, as long as the good physical properties of the polyimide obtained by the method of the present invention are not impaired, 1
There is no problem in using a part in place of another diamine.

As a diamine that can be used as a partial substitute,
For example, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, bis (3-aminophenyl) ether, (3-aminophenyl) (4-aminophenyl) ether , Bis (4-aminophenyl) ether, bis (3-aminophenyl) sulfide, (3-
Aminophenyl) (4-aminophenyl) sulfide,
Bis (4-aminophenyl) sulfide, bis (3-aminophenyl) sulfoxide, (3-aminophenyl)
(4-aminophenyl) sulfoxide, bis (4-aminophenyl) sulfoxide, bis (3-aminophenyl) sulfone, (3-aminophenyl) (4-aminophenyl) sulfone, bis (4-aminophenyl) sulfone, 3 , 3'-Diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4'-diaminobenzophenone, bis [4- (4-aminophenoxy) phenyl] methane,
1,1-bis [4- (4-aminophenoxy) phenyl]
Ethane, 1,2-bis [4- (4-aminophenoxy) phenyl] ethane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-amino Phenoxy) phenyl] butane, 2,2-bis [4-
(4-aminophenoxy) phenyl] -1,1,1,3,3,3-
Hexafluoropropane, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, 1,4-bis (4 -Aminophenoxy) benzene, 4,4'-bis (4-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl]
Sulfide, bis [4- (4-aminophenoxy) phenyl] sulfoxide, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4 -Aminophenoxy) phenyl] ether, 1,4-bis [4-
(3-aminophenoxy) benzoyl] benzene, 1,3
-Bis [4- (3-aminophenoxy) benzoyl] benzene, bis [4- (3-aminophenoxy) phenyl] methane, 1,1-bis [4- (3-aminophenoxy) phenyl] ethane, 2,2 -Bis [4- (3-aminophenoxy) phenyl] propane, 2- [4- (3-aminophenoxy) phenyl] -2- [4- (3-aminophenoxy) -3-methylphenyl] propane, 2, 2−
Bis [4- (3-aminophenoxy) -3-methylphenyl] propane, 2- [4- (3-aminophenoxy)
Phenyl] -2- [4- (3-aminophenoxy) -3,
5-dimethylphenyl] propane, 2,2-bis [4- (3
-Aminophenoxy) -3,5-dimethylphenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] butane, 2,2-bis [4- (3-aminophenoxy) phenyl] -1 , 1,1,3,3,3-hexafluoropropane, 4,4'-bis (3-aminophenoxy) biphenyl, 4,4'-bis (3-aminophenoxy) -3-methylbiphenyl, 4,4 '-Bis (3-aminophenoxy)
-3,3'-dimethylbiphenyl, 4,4'-bis (3-aminophenoxy) -3,5-dimethylbiphenyl, 4,4'-bis (3-aminophenoxy) -3,3 ', 5,5 '-Tetramethylbiphenyl, 4,4'-bis (3-aminophenoxy) -3,3'-dichlorobiphenyl, 4,4'-bis (3-
Aminophenoxy) -3,5-dichlorobiphenyl, 4,4 ′
-Bis (3-aminophenoxy) -3,3 ', 5,5'-tetrachlorobiphenyl, 4,4'-bis (3-aminophenoxy) -3,3'-dibromobiphenyl, 4,4'-bis (3
-Aminophenoxy) -3,5-dibromobiphenyl, 4,
4'-bis (3-aminophenoxy) -3,3 ', 5,5'-tetrabromobiphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl Sulfide, bis [4- (3-aminophenoxy) -3-methoxyphenyl] sulfide,
[4- (3-aminophenoxy) phenyl] [4- (3
-Aminophenoxy) -3,5-dimethoxyphenyl] sulfide, bis [4- (3-aminophenoxy) -3,5
-Dimethoxyphenyl] sulfide, bis [4- (3-
[Aminophenoxy) phenyl] sulfone, and these may be used alone or as a mixture of two or more.

Further, as R of the tetracarboxylic dianhydride represented by the formula (II) used in the method of the present invention, Selected from the group consisting of: These tetracarboxylic dianhydrides are used alone or in combination of two or more.

Further, Z of the aromatic monoamine represented by the formula (III) used in the method of the present invention is as follows: Selected from the group consisting of

The molar ratio of tetracarboxylic dianhydride, aromatic diamine and aromatic monoamine used in the method of the present invention is 0.9 to 1.0 mol of aromatic diamine and 1 mol of aromatic monoamine per mol of tetracarboxylic dianhydride. Is 0.00
It is a ratio of 1 to 1.0 mol.

In the production of polyimide, it is customary to adjust the ratio of tetracarboxylic dianhydride to aromatic diamine in order to adjust the molecular weight of the resulting polyimide.
In the method of the present invention, in order to obtain a polyimide having good melt flowability, the molar ratio of the aromatic diamine to the tetracarboxylic dianhydride is from 0.9 to 1.0.

The co-existing aromatic monoamine is used in an amount of 0.001 to 1.0 mol based on tetracarboxylic dianhydride. If the amount is less than 0.001 mol, the thermal stability at a high temperature intended for the present invention cannot be obtained. If the amount is more than 1.0 mol, the mechanical properties deteriorate. The preferred amount is 0.01 to 0.
The ratio is 5 mol.

In the method of the present invention, all known methods for producing polyimide can be used, but it is particularly preferable to carry out the reaction in an organic solvent.

Examples of the organic solvent used in this method include N, N-dimethylformamide, N, N-dimethylacetamide, N, N
-Diethylacetamide, N, N-dimethylmethoxyacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N-methylcaprolactam, 1,2-dimethoxyethane, bis (2-methoxyethyl ) Ether, 1,2-bis (2-methoxyethoxy) ethane, bis {2- (2-methoxyethoxy) ethyl} ether, tetrahydrofuran, 1,3-dioxane, 1,4-
Dioxane, pyridine, picoline, dimethyl sulfoxide, dimethyl sulfone, tetramethyl urea, hexamethyl phosphoramide, phenol, m-cresol, p-
Cresol, p-chlorophenol, anisole and the like can be mentioned. These organic solvents may be used alone or in combination of two or more.

The method of adding tetracarboxylic dianhydride, aromatic diamine, aromatic monoamine to the organic solvent in the method of the present invention and reacting the same includes (a) reacting tetracarboxylic dianhydride with aromatic diamine, (B) a method in which an aromatic monoamine is added and the reaction is continued, (b) a method in which an aromatic monoamine is added to a tetracarboxylic dianhydride to cause a reaction, and then an aromatic diamine is added and the reaction is further continued; Any addition method may be employed, such as a method of simultaneously adding and reacting a carboxylic dianhydride, an aromatic diamine, and an aromatic monoamine.

The reaction is carried out in a temperature range from 0 ° C to 250 ° C. Usually, it is performed at a temperature of 60 ° C. or less.

 The reaction pressure is not particularly limited, and the reaction can be sufficiently performed at normal pressure.

The reaction temperature varies depending on the type of tetracarboxylic dianhydride, aromatic diamine, aromatic monoamine, solvent used and the reaction temperature, but usually 4 to 24 hours is sufficient.

By such a reaction, a polyamic acid comprising a repeating unit represented by the following formula (V) is produced.

(Wherein R is the same as described above). The polyamic acid is dehydrated by heating to 100 to 400 ° C. or chemically imidized using a commonly used imidizing agent, for example, triethylamine and acetic anhydride. A corresponding polyimide comprising the repeating unit of IV) is obtained.

(Wherein R is the same as above.) In general, after forming polyamic acid at a low temperature,
Further, it is thermally or chemically imidized. However, at a temperature of 60 ° C. to 250 ° C., polyimide can be obtained by simultaneously performing the polyamic acid generation and the thermal imidization reaction. That is, after the aromatic diamine, tetracarboxylic dianhydride, aromatic monoamine is suspended or dissolved in an organic solvent, the reaction is carried out under heating, and the polyamic acid generation and the dehydration imidization are simultaneously performed to form the above. A polyimide comprising the repeating unit of the formula (IV) can also be obtained.

In addition, without using an organic solvent, a method of obtaining a polyimide by mixing a tricarboxylic acid dianhydride, an aromatic diamine, and an aromatic monoamine, and treating the mixture in the presence or absence of a dehydrating agent, or the like. Is also used.

When subjecting the polyimide of the present invention to melt molding, other thermoplastic resins within a range that does not impair the purpose of the present invention, for example,
An appropriate amount of polyethylene, polypropylene, polycarbonate, polyarylate, polyamide, polysulfone, polyethersulfone, polyetherketone, polyphenylenesulfide, polyamideimide, polyetherimide, modified polyphenylene oxide, etc. can be blended in an appropriate amount depending on the purpose. . Further, the following fillers and the like used in ordinary resin compositions may be used to the extent that the object of the invention is not impaired. That is, graphite,
Abrasion resistance improvers such as carborundum, silica stone powder, molybdenum disulfide, and fluororesin; reinforcing materials such as glass fiber, carbon fiber, boron fiber, silicon carbide fiber, carbon whisker, asbestos, metal fiber, and ceramic fiber; and trioxide Flame retardant improvers such as antimony, magnesium carbonate, calcium carbonate, etc., electric property improvers such as clay and mica, tracking improvers such as asbestos, silica, graphite, etc., acid resistance such as barium sulfate, silica, calcium metasilicate, etc. Improver, iron powder, zinc powder,
Thermal conductivity improvers such as aluminum powder and copper powder, other glass beads, glass spheres, talc, diatomaceous earth, alumina,
Shirasubarun, hydrated alumina, metal oxides, coloring agents and the like.

[Examples] Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

Example 1 A reactor equipped with a stirrer, a reflux condenser and a nitrogen inlet tube was charged with 218 g (1.0 mol) of pyromellitic anhydride and 4550 g of N, N-dimethylacetamide, and bis {4- [4-
(4-Aminophenoxy) phenoxy] phenyl} sulfone (585.8 g, 0.95 mol) was added portionwise at room temperature under a nitrogen atmosphere while paying attention to the rise in solution temperature, and the mixture was stirred at room temperature for about 20 hours. The logarithmic viscosity of the polyamic acid obtained at this time was 0.56 dl / g. The logarithmic viscosity is a value measured at 35 ° C. using a solvent of N, N-dimethylacetamide at a concentration of 0.5 g / 100 ml (the same applies hereinafter).

9.3 g (0.10 mol) of aniline was added to this polyamic acid solution at room temperature under a nitrogen atmosphere, and the mixture was further stirred for 1 hour. Then, to this solution, 202 g (2 mol) of triethylamine and 306 g (3 mol) of acetic anhydride were added dropwise. About 2 hours after the completion of the dropping, yellow polyimide powder began to precipitate.
After further stirring at room temperature for 20 hours, the reaction product was discharged into methanol and filtered. Further, it is dispersed and washed in methanol, filtered,
After drying at 180 ° C. for 2 hours, 736 g of polyimide powder was obtained.
The glass transition temperature of this polyimide powder is 285 ° C, and the melting point is 420.
° C (by DSC; the same applies hereinafter).

Using the polyimide powder obtained in this example, with a Koka type flow tester (manufactured by Shimadzu Corporation, CFT-500), a diameter of 0.1 cm,
The melt viscosity was repeatedly measured using an orifice having a length of 1 cm. After maintaining at 440 ° C for 5 minutes, 100kg / cm ²
Extruded with pressure. A test of crushing the obtained strand and extruding it under the same conditions was performed five times in succession.

FIG. 1 shows the relationship between the number of repetitions and the melt viscosity. Even if the number of repetitions increases, there is almost no change in the melt viscosity, indicating that the thermal stability is good.

Comparative Example 1 729 g of polyimide powder was obtained in exactly the same manner as in Example 1 except that the operation of reacting aniline was not performed.

Using this polyimide powder, a repeated test of the melt viscosity was performed by a flow tester in the same manner as in Example 1, and the results shown in FIG. 1 were obtained.

As the number of repetitions increased, the melt viscosity increased, and the thermal stability was inferior to that of the polyimide obtained in Example 1.

Example 2 In the same apparatus as in Example 1, 294 g (1.0 mol) of 3,3 ', 4,
4'-biphenyltetracarboxylic dianhydride and 14 g (0.
1586) aniline and dimethylacetamide 4986g
And bis {4- [4- (4-aminophenoxy)
[Phenoxy] phenyl} sulfone (585.8 g, 0.95 mol) was added at room temperature under a nitrogen atmosphere while paying attention to the rise in solution temperature, and the mixture was stirred at room temperature for about 20 hours. The logarithmic viscosity of the obtained polyamic acid was 0.51.

Next, 202 g (2 mol) of triethylamine and 306 g (3 mol) of acetic anhydride were added dropwise to this solution. The mixture was stirred for 20 hours to obtain a pale yellow slurry. The slurry was filtered, washed with methanol, and dried under reduced pressure at 180 ° C. for 8 hours.
10 g of a pale yellow polyimide powder was obtained. The glass transition temperature of this polyimide powder was 261 ° C.

The molding stability of the polyimide obtained in this example was measured by changing the residence time in the cylinder of the flow tester. The temperature was 380 ° C. and the pressure was 100 kg / cm ² . FIG. 2 shows the results. Even if the residence time in the cylinder becomes longer, the melt viscosity hardly changes, indicating that the thermal stability is good.

Comparative Example 2 A pale yellow polyimide powder was obtained in exactly the same manner as in Example 2 except that aniline was not used.

The glass transition temperature of the polyimide powder was 261 ° C. When the residence time in the flow tester cylinder was changed and the melt viscosity was measured in the same manner as in Example 2, the melt viscosity increased as the residence time became longer, and the heat stability was higher than that of the polyimide obtained in Example 2. It was inferior.

Example 3 Bis {4- [4- (4-aminophenoxy) phenoxy] phenyl} sulfone 585 was prepared in the same apparatus as in Example 1.
8 g (0.95 mol), bis (3,4-dicarboxyphenyl)
310 g (1.0 mol) of ether dianhydride, 9.3 g (0.1
0 mol) and 3570 g of m-cresol, and heated to 150 ° C. while stirring under a nitrogen atmosphere, followed by stirring for 3 hours, and then filtered to obtain a polyimide powder. Further, this polyimide powder was washed with methanol and acetone and purified. The glass transition temperature of this polyimide powder was 235 ° C.

As in Example 1, when the melt viscosity was measured by repeatedly extruding with a flow tester at a temperature of 360 ° C. and a pressure of 100 kg / cm ² , almost no change in the melt viscosity depending on the number of measurements was observed. FIG. 3 shows the results.

Comparative Example 3 To the polyamic acid solution obtained in Example 1, 9.3 g (0.10 mol) of aniline was added in the same manner as in Example 1, and 1 part of aniline was added.
After stirring for a while, this polyamic acid solution was poured into a large amount of ethyl ether to precipitate and separate the polyamic acid. The polyamic acid powder thus obtained was dried at 35 ° C. in a nitrogen stream, and then dried in an oven filled with inert gas.
3 hours at 0 ° C, then 1 hour at 200 ° C,
After a time treatment, a polyimide was obtained. The logarithmic viscosity of this polyimide was 0.55 dl / g. The thermal stability of this polyimide was evaluated in the same manner as in Example 1. As a result, the intermediate value between Example 1 and Comparative Example 1 was shown. That is, although improved compared to Comparative Example 1, it was not sufficient, and compared with Example 1, there was a remarkable difference in repeated melt viscosity, and it was confirmed that the melt viscosity was not endurable for repeated use of melt molding.

[Effects of the Invention] According to the method of the present invention, it is excellent in mechanical properties, thermal properties, electrical properties, solvent resistance, heat resistance, thermal stability for a long time, and moldability. An excellent polyimide can be provided.

[Brief description of the drawings]

1 and 3 are graphs showing the relationship between the number of times of melting of the polyimide of the present invention and the melt viscosity, and FIG. 2 is a graph showing the relationship between the residence time of the polyimide of the present invention in the flow tester cylinder and the melt viscosity.

Claims (1)

(57) [Claims] (1) The following formula (I) And (b) an aromatic diamine represented by the following formula (II): (Where R is Represents a tetravalent group selected from the group consisting of A tetracarboxylic dianhydride represented by the following formula (III): Z-NH ₂ (III) (where Z is Represents a monovalent group selected from the group consisting of (D) the amount of aromatic diamine is 0.9 to 1.0 mole ratio per mole of tetracarboxylic dianhydride, and the amount of aromatic monoamine is tetracarboxylic dianhydride 1 0.00 per mole
Reacting at a molar ratio of 1 to 1.0, characterized by the formula (IV) (Wherein R is as defined in the formula (II).) A polyimide having good thermal stability, wherein the terminal of the polymer is a group of the formula (IV-a) Production method. (In the formula, R and Z are as defined above.)